====== Pearl formation ======

Pearls are the only 'gems' produced by a living organism. Their formation process (either by natural means or through human intervention) is a response to an injury in an oyster's 'mantle' tissue, such as an intrusion by a foreign body, e.g. a sand grain etc.

The exact mechanisms for the glossy pearl formation are unclear.

>__Nature's ability to generate so amazingly complex structures like a pearl is impressive and still partially unknown. [...]__ Such a challenge will strongly encourage the community to continue to develop approaches and knowledge to decipher the biophysical and molecular details of biomineralization processes." 
>\\ "[...] our fundamental understanding of nacre formation remains limited. Few studies are available that explain the pearl mineralization process as well as the formation of defects [...]"\\ \\ Source : [[http://rsos.royalsocietypublishing.org/content/2/7/150144|Yes, it turns: experimental evidence of pearl rotation during its formation]] {{:oa_padlock_grn.png?16&nolink|Open Access}}//Royal Society, Open Science//

The 2105 study from //Université de la Polynésie Française// experimentally demonstrated, for the first time, that pearls rotate inside the oyster during their formation - perhaps contributing to their rounded form.

//Note:// As the quote above explains, the formation of nacre - the material which forms not only pearls but also the shells of marine molluscs in general - has not been fully explained.